1. Field of the Invention
This invention relates, in general, to the field of surgical devices for removal of cataracts from a person's eye and, in particular, to apparatus employing aspiration and irrigation for extracapsular extraction of an opaque lens, with or without a nucleus, or cataract from an eye of a patient.
2. Description of the Prior Art
It is well known that cataracts are caused by opacification of the lens of the eye. At about age 20, a person's lens forms a nucleus which becomes larger and harder with age. The material surrounding the nucleus of a cataractous lens is known as the cortex. Depending upon its severity, cataracts cause poor vision or even an almost complete inability to see. While old age is probably the primary cause of cataracts, there are other causes. Thus, cataracts have been known to exist in every age group and in every race. There are records verifying knowledge of the existence of cataracts dating back for many centuries.
There is only one type of treatment for cataracts: surgery. There are no drugs or other treatment which will make cataracts dissolve or disappear. Usually age and the amount and degree of opaqueness is determinative of whether or not surgery is warranted. In children, the lens is soft and flexible and a clear lens is able to change its power accommodation. In older persons, the lens is less resilient and cannot very well adjust near focus. In the latter case, glasses can correct the deficiency. However, as previously stated, surgery is the only treatment for cataracts whether the patient is young or old.
Since cataracts only affect the lens of an eye, removal of the lens and its replacement by either glasses, contact lenses, or the newly devised technique of lens implantation can and does restore a person's sight. Many techniques, each with its own disadvantages and advantages for removal of the lens, have been developed over the ages. Understandably, the early techniques were not very successful, while modern day techniques are highly successful. Cataract surgery originated in India, Greece and Arabia. The first known procedure of cataract surgery, which dates back to the first century, is alternatively termed as couching, depression, or reclination. In that technique, the opaque lens is displaced into the vitreous humor of the eyeball. This early operative technique caused various complications that often led to blindness. Development of the couching technique, by different operating methods and equipment, tended to lessen the effect and after effects of the surgery, but could not and did not eliminate its basic deficiencies or limitations. As a result, totally different surgical methods were needed and were developed.
A technique, known today as the aspiration method, was probably first used shortly after the inception of the couching technique. However, the first written description of the aspiration method did not appear until the eleventh century. An Arabian ophthalmologist by the name of Ammar ibn Ali is generally credited as being the inventor of the method of aspiration because, in part, of his approach which avoided a failure known as humor loss. By entering the eye through the sclera instead of the cornea, Ammar ibn Ali was able to prevent loss of aqueous humor which would have resulted by entering the eye through the cornea.
In 1745, Jacques Daviel of France, made an incision in the lower margin of the eye, cut through the lens capsule, and extracted the cataract. His innovation overcame many of the complications caused by the couching technique and was considered highly successful. Modern variations of the innovations of Daviel and Ali have resulted in today's routine methods of cataract removal which are virtually one-hundred percent successful.
Regardless of whether a cataract is removed by aspiration, or actually delivering the cataract from the eye, or by a combination of these methods, surgical removal of cataracts in today's technology is broadly classified as intracapsular or extracapsular removal. With intracapsular removal, the lens and its outer covering, the lens capsule, are both removed. With extracapsular removal, the anterior portion of the lens capsule is cut away from the lens and the cataract is then removed. Intracapsular extraction of cataracts is the most prevalent technique employed by today's ophthalmologists.
A relatively good history of the techniques employed to remove cataracts may be found in, "Aspiration Method of a Hard Cataract," by Yasuharu Kuwahare, M.D., Igaku Shoin Ltd., Tokyo, 1972. Another reference is, "Phacoemulsification and Aspiration," "The Kelman Technique of Cataract Removal," by Charles D. Kelman, M.D. Aesulapius Publishing Co., Ala., 1975. These references also contain information concerning the equipment or apparatus utilized to aspirate both hard and soft cataracts from an eye. In referring to these references, however, it is to be realized that the subject matter of this patent application applies only to aspiration and irrigation apparatus which aspirates either soft cataracts or the cortex of hard cataracts by th extracapsular technique.
Typically, modern aspiration and irrigation apparatus includes a handpiece, held by the operating surgeon, having suction and irrigation lines connected thereto and a needle eminating therefrom. The suction line is usually connected to a vacuum pump. In the past, a syringe or the surgeon's mouth was used to create the vacuum which sucked the lens from the eye. The irrigation line is connected to a reservoir of appropriate liquid which is pumped to the anterior chamber of the eye to maintain its form during the surgery. The needle, having both suction and irrigation capabilities is inserted through an incision in the eye and is placed in physical contact with the lens to effectuate aspiration.
The irrigation-aspiration apparatus of the prior art is made to be reused for an unlimited number of operations; hence, it is required that it be capable of being sterilized. The reuseable requirement also results in the requirement that the vacuum and fluid connections be resealable time after time after disassembly or after needle or handpiece changes. It also requires exact fits between the interchangeable components.
Because of the hard service experienced by the prior art apparatus, it had to be designed to be very strong; hence, it is usually heavy and relatively unwieldly. Metal tubing or other devices connected to the outer surface of the handpiece also contribute to inadequate handling characteristics. Needless to say, cataract surgery is a very delicate operation and proper maneuverability of the aspiration and irrigation needle is an essential requirement. Naturally, therefore, proper gripping characteristics of the handpiece and lack of external obstructions on the handpiece are prerequisites to proper placement of the needle within the eye and its subsequent manipulation. The apparatus of the prior art suffers from a lack of adequate handling characteristics.
In that the devices of the prior art are reuseable, it is not uncommon for dried and hard pieces of aspirated portions of the eye to be lodged within the instrument or its tubing. Such a situation causes inconsistent vacuum levels, or unknown vacuum levels at the tip of the aspiration needle, or even worse, actual blockage of the vacuum. This leads to inconsistencies from one operation to another. Indeed, over a prolonged number of operations, the device may fail to function entirely and such failure may occur at a most inopportune time.
Another problem associated with the devices of the prior art involve kinking of the permanent tubing attached to the devices. This may occur from dropping the device during its long lifetime or from abuse during cleaning, assembly or disassembly of the unit. Of course, straightening of the kink will somewhat correct this condition, but permanent damage may have occured such as a fracture of the metal. Consider such possibilities and the effects of the same in view of the distinct probability that the operating surgeon is not aware of the defective condition.
Accordingly, it is an object of the present invention to provide irrigation-aspiration apparatus for use with extracapsular extraction of cataracts which requires no operating room sterilization and is disposable after one operation.
Another object of the present invention is to provide a surgical device which does not require assembly prior to use by the operating surgeon.
A further object of the invention is to provide cataract surgical apparatus which assures leak-free and vacuum-tight joint connections.
A still further object of the present invention is to provide apparatus for cataract surgery which is virtually kinkless.
An even further object of the invention is to provide a disposable device which assures consistency of vacuum flow and irrigation flow from one device to another.
Still an even further object of the present invention is to provide apparatus which is lightweight and easily maneuvered by the operating surgeon to allow precise location and movement of the aspiration and irrigation tips within the eye.
Another object of the present invention is to provide a device which does not necessitate disconnecting and reconnecting different handpieces to obtain irrigation without aspiration.